Method and means for shaping parts by hydraulic extrusion

ABSTRACT

A method for shaping parts by hydraulic extrusion, which allows deforming the billet by different pressures exerted upon different billet zones. The method is embodied in a device which comprises a vessel housing, and a plurality of auxiliary vessels whereof the edges are pressed against the billet, defining closed cavities therewith. Liquid under pressure is supplied into each of these cavities. The manufactured parts have a negligible wall thickness error. The method permits manufacturing doublecurvature parts.

United States Patent [1 1 Ershov et al.

[451 Oct. 7, 1975 [54] METHOD AND MEANS FOR SHAPING PARTS BY HYDRAULICEXTRUSION [76] Inventors: Vladislav Ivanovich Ershov, ulitsa Volgina,19, kv. 16; Nikolai Dmitrievich Livenko, ulitsa Profsojuznaya, 100,korpus 4, kv. 198, both of Moscow, U.S.S.R.

22 Filed: Oct.l9,1973

21 Appl. No.: 408,004

[30] Foreign Application Priority Data Mar. 30, 1973 U.S.S.R 1902339July 5, 1973 U.S.S.R 1931501 [52] US. Cl 72/57;.29/421 [51] Int. Cl.B21D 26/04 [58] Field of Search 72/28, 57, 54, 60, 63, 72/347; 29/421[56] References Cited UNITED STATES PATENTS 2,284,773 6/1942 Sivian eta1. 72/57 2,728,317 12/1955 Clevenger et al 72/57 2,960,141 11/1960Rutter 72/58 3,420,089 1/1969 Myers 72/351 3,566,650 3/1971 Johnson72/60 3,715,902 2/1973 Fuchs, .lr. 72/60 Primary Examiner-Richard J.Herbst Attorney, Agent, or Firm-Waters, Schwartz & Nissen [57] ABSTRACTA method for shaping parts by hydraulic extrusion, which allowsdeforming the billet by different pressures exerted upon differentbillet zones. The method is embodied in a device which comprises avessel housing, and a plurality of auxiliary vessels whereof the edgesare pressed against the billet, defining closed cavities therewith.Liquid under pressure is supplied into each of these cavities. Themanufactured parts have a negligible wall thickness error. The methodpermits manufacturing double-curvature parts.

8 Claims, 6 Drawing Figures US Patent 0a. 7,1975 Sheet 1 of3 3,910,086

m at v w mt US. Patent Oct. 7,1975 Sheet 2 of3 3,910,086

FIE 5 U.S. Patent Oct. 7,1975 Sheet 3 of3 3,910,086

\ kw m METHOD AND NIEANS FOR SHAPING PARTS BY HYDRAULIC EXTRUSION Thepresent invention relates to methods and equipment for pressure shapingof metals and more particularly to methods for shaping parts byhydraulic extrusion and devices utilizing such methods.

This invention may find application in various branches of mechanicalengineering where it may be required to obtain complex-shaped parts,such as, for instance, convexo-concave pieces, with walls of uniformthickness.

it is widely practised in the art to shape parts by hydraulic extrusionwhereby a billet is deformed by water supplied under pressure.

it is likewise known in the art to employ hydraulic extruders comprisinga vessel communicating with a source of pressurized liquid supply thebillet being mounted on said vessel, and clamping means fastening thebillet about the outer periphery thereof to the vessel. Besides, a diewith a cavity shaped like the. desired part is mounted on the billet.The clamping means in the known extruder is constituted by a plate witha hole or a ring arranged intermediate the vessel and the billet so asto press the billet edge against the die.

The pressure of the billet against the vessel is to provide for thetightness of the vessel through the entire process of part shaping. Thispressing force is provided in the known extruders by hydraulic pressesor special devices formed as massive trusses coupled with hydrauliccylinders.

The die of the known extruder is generally made of steel or concretereinforced with steel elements which provide the required degree ofstiffness and which enable the die to withstand the force of pressurethereof against the vessel as well as the pressure of the liquid at thefinal instant of billet deformation when the billet comes into contactwith the die. The cavity of the die is vented to the atmosphere toremove air in the process of part formation.

Extruding parts by the known method in the known extruder, pressurizedliquid is supplied into the vessel and the pressure of the liquid isgradually raised to the value required to deform the billet. The billetedge clamped between the die and the vessel is likewise deformed,becoming smaller, thicker and forming folds or corrugations. The lineardisplacement of the billet edge is determined by the extrusion ratio setfor each kind of material depending on its mechanical properties, aswell as on the size of the part and the thickness of the billet.

The liquid transmits to the billet a pressure which is constant over itsentire surface. The shape of the billet in the process of extrusion,before it is pressed against the die, is set randomly depending on thesize of the billet and the mechanical properties of the billet material.

The known method for shaping parts by hydraulic extrusion has limitedapplication for the reason that the parts manufactured thereby havewalls manifestly differing in thickness. The wall thicknessnon-uniformity reaches 45 per cent, with the corresponding deteriorationof quality. According to the known method, extrusion is usually carriedout at such pressures of the liquid would permit avoiding loss ofstability folding in the billet zone adjacent the clamping means. Tothis end, the pressure in the vessel is raised so as to slightly exceedthe value required to deform the central portion of the billet, with theresult that the billet mate rial is thinned non-uniformly in the processof extrusion. This constitutes a material drawback of the known methodfor shaping parts of hydraulic extrusion.

The known hydraulic extruder has further disadvantages, inter alia, theunavoidable need for a die. The latter is usually very bulky and heavy;furthermore, the die is extremely labour-intensive in manufacture as thesurface of its cavity is to be finished to allow for an elasticspringback of the part after the deforming load has springback of thepart after the deforming load has been relieved.

Another disadvantage of the known extruder consists in that, to put upthe necessary force to press the billet to the vessel and the die to thebillet, it takes either powerful hydraulic equipment or special clampingmeans which are to be manufactured specially for each part size and foreach kind of material. For this purpose use is made of screw jacks orhydraulic cylinder mounted at various points about the periphery of thebillet. Therefore, in the process of extrusion, the edges of the billetare pressed non-uniformly, which constitutes a quality risk.

Besides, with this arrangement, the pressing force control in theprocess of extrusion is a difficult matter.

It is an object of the invention to provide such a method of shapingparts by hydraulic extrusion which would yield complex-shaped parts withwalls of uniform thickness.

it is another object of the invention to provide a hydraulic extruderwherein liquid would be supplied to different billet zones of differentpressures.

It is a further object of the invention to provide a hydraulic extruderof a fairly simple and reliable design.

With these objects in view, there is provided a method for shaping partsby hydraulic extrusion whereby billets are profiled by liquid suppliedunder pressure, wherein, in accordance with the invention, liquid issupplied simultaneously to different zones of the billet at differentpressures corresponding to the desired part shape which is periodicallychecked as it is evolving in the process of extrusion.

To implement the method of the invention and to attain the foregoingobjectives, there is provided a device comprising a vessel, whichcommunicates with a source of pressurized liquid supply and whereon thebillet is mounted, as well as clamps to fasten the billet to the vesselabout the periphery thereof. in accordance with the invention, in thehead of the vessel there is installed with one end thereof a guidemember carrying a plurality of auxiliary vessels sequentially arrangedso as to reciprocate freely along the guide member and adapted to fitone into another, the edges of these auxiliary vessels being pressedagainst the billet so that each pair of adjacent vessels defines withthe billet a hermetically sealed cavity, each cavity being hydraulicallyconnected to the pressurized liquid supply, and the areas of the outerand inner surfaces of each auxiliary vessel are determined by thedifference in the loads exerted thereupon by the pressure of the liquidin said cavities adjoining the vessel on both sides so that the loadinside the vessel is somewhat smaller than that outside the vessel.

In a device of this design, liquid may be supplied to different billetzones defined by the edges of the auxiliary vessels at differentpressures to obtain parts with walls of uniform thickness.

It the part to be manufactured has in intricate shape comprising interalia, numerous mating convex and concave surfaces, it is preferred thatthe device should include, mounted on the billet, a vessel, such as theone described hereinabove, in the head of which there is installed withone end thereof a guide member carrying a plurality of auxiliary vesselsarranged so as to reciprocate freely therealong, said auxiliary -vesselsbeing adapted to fit one into another. The edges of said auxiliaryvessels are clamped in the billet in the interspaces between the edgesof the auxiliary vessels disposed beneath the billet so that each pairof adjacent vessels dcfines with the billet a hermetically sealedcavity, each cavity being hydraulically connected to the source ofpressurized liquid supply, and the areas of the outer and inner surfacesof each of the auxiliary vessels are determined by the difference in theloads exerted thereupon by the pressure of the liquid in the cavitiesadjoining the vessel on both sides so that the load inside the vessel issomewhat smaller than that outside the vessel.

In one embodiment of the invention, the guide member to carry theauxiliary vessels reciprocating therealong is constituted by a hollowbar connected to the movable member ofa hydraulic cylinder, andcarrying, sequentially fitted thereover, a plurality of springs whichconstrain the auxiliary vessels to stay at a certain distance one fromanother and which also serve to press the auxiliary vessels to thebillet prior to the start of operating.

If the dimensions of the part in plan are smaller than those of thevessel, it is preferred that between the vessel and the billet thereshould be positioned at least one plate fastened to the billet and tothe vessel by a clamp and having a hole to fit the contour of the partin plan.

Each of the auxiliary vessels disposed above the billet shouldpreferably house a conduit rigidly connected thereto, which conduit isintended to vent the air out of the vessel as it is being filled withthe liquid. The conduit has an outlet close to the edge of the vesseland comprises a portion extending beyond the confines of the extruderparallel to the guide member and equipped with a valve which serves,inter alia, to monitor the displacements of the auxiliary vessel in theprocess of billet deformation.

In an alternative embodiment of the invention, each of the auxiliaryvessels has a bushing adjacent the head thereof, which bushing is fittedover the guide bar and carries a spring constraining the auxiliaryvessels to stay apart one from another, the bushings of adjacentadditional vessels being adapted to telescopically fit one into another.

These bushings may be used to vary the areas of the inner or outersurfaces of the auxiliary vessels to comply with the abovementionedratio of the loads exerted by the pressure of the liquid thereupon.

The present invention is illustrated both as to the method and apparatusthereof in the accompanying drawings, wherein:

FIG. 1 is a schematic representation of a hydraulic extruder inaccordance with the invention, shown before the start of operation;

FIG. 2 is the hydraulic extruder of FIG. 1 in the process of shaping apart;

FIG. 3 is an elevational view of a hydraulic extruder, showing it in twopositions: set for operation (left) and at the final instant of billetdeformation;

FIG. 4 is a view, partially in section, of an embodiment of thehydraulic extruder of this invention;

FIG. 5 is an elevational view, partially in section, of an embodiment ofthe hydraulic extruder of this invention; and

FIG. 6 is a blown-up view of position VI of FIG. 5.

Referring now to FIG. 1, there will be seen to be schematicallyillustrated therein a hydraulic extruder set for operation, and in FIG.2 the same hydraulic extruder is represented at the instant of partshaping effected by way of simultaneously supplying liquid to differentportions of the billet under different pressures P P P and P Theproposed hydraulic extruder comprises a vessel I mounted on a base 2.The vessel 1 is shaped like a body of revolution, such as a cone orellipsoid, and has relatively thick walls designed to withstandpressures of up to atm. In the cavity of the-vessel 1 there are aplurality of auxiliary vessels 3 arranged sequentially along a guidemember installed in the head of the vessel 1. The number of theauxiliary vessels 3 is chosen depending on the size and shape of thevessel 1. On the vessel 1 there is mounted a billet 4 which is incontact with the edges of the auxiliary vessels 3 provided with seals 5.Between the billet 4 and two adjacent auxiliary vessels, for example 1and 3 or 3 and 3, there are formed hermetically sealed auxiliarycavities. A. Each of the auxiliary cavities A is hydrualically connectedto pressurized liquid supply 6 by conduits 7 comprising reducing valves8 which control pressure in each conduit 7. The conduits 7 extend intothe wall of the vessel 1 through holes specially provided therein. Theseholes also house airtight inlets 9 formed as nipples. The airtight inlet9 is connected on one side to the conduit 7 and on the other side to aflexible conduit 10. Each of the flexible conduits 10 is designed tosupply the liquid to the respective auxiliary cavity A. In the walls ofthe auxiliary vessels 3, at the points where the flexible conduit 10passes from one auxiliary cavity A to another, holes are defined withairtight inlets 9 fitted therein as well. Each conduit 7 is providedwith a valve 11 to drain liquid from the respective auxiliary cavity Awhich is mounted on a branching-out conduit 11a, the latter insertedinto a main which is connected to the pressurized liquid supply 6.

The areas of the outer and inner surfaces of each auxiliary vessel 3 aredetermined by the difference in the loads exerted thereupon by thepressure of the liquid in the auxiliary cavities A adjoining theauxiliary vessel so that the pressure load inside the vessel 3 should besomewhat lower than that outside this vessel 3. Accordingly the walls ofeach auxiliary vessel 3 are made gradually thickening or thinning fromthe edges toward the head thereof. If this condition is complied with,in each of the auxiliary cavities A there may be provided a pressurevalue to a certain extent higher than those in the adjacent lowerdisposed cavities A. At the same time the pressure differential betweenthe adjacent cavities never rises beyond a safety limit up to which thejoint between the edge of the respective auxiliary vessel 3 and thebillet 4 stays airtight. The billet 4 is pressed against the edge of thevessel I by clamping means 12 formed as a ring with a hole conforming inshape to the contour of the part being manufactured in plan, theclamping ring being bolted to the vessel 1 (the bolts are not shown).

Should the extruded part and, hence, its billet fail to completely coverthe vessel 1, use is made of a superposed plate 13 (FIG. 4) with a holeconforming in shape to the contour of the part in plan. The plate 13 ismounted on the edges of the vessel 1 so as to span a certain number ofthe auxiliary cavities A. The billet 4 is positioned on the plate 13 andfastened thereto by the clamping means 12. The plate 13 must be stiffenough to withstand the pressure of the liquid in the auxiliary cavitiesA spanned thereby without strain.

The auxiliary vessels 3 are mounted in the vessel 1 so as to reciprocatefreely along the guide member thereof. To this end, in the head portionsof all vessels 1 and 3 there are defined holes coaxially one withanother to receive a hollow bar 14 which serves as the guide member.These holes have fitted therein sealing rings 15 which envelop thehollow bar 14 and ensure the airtightness of the auxiliary cavities A.Over the hollow bar 14 there are fitted springs 16 which separate theauxiliary vessels 3 one from another and press the edges of theauxiliary vessels 3 against the billet 4 before the extruder is started.The hollow bar 14 is connected to the sliding member of a hydrauliccylinder 17 (FIGS. 3 and 5), in this case to a cylinder rod 18. Cavity Bof the bar 14 is also hydraulically coupled via a T- valve 19 with thepressurized liquid supply 6. The free end of the bar 14 which is incontact with the billet 4 is formed as a flange 20 with a seal 5adjoining the bar 14.

The T-valve 19 also serves to vent the cavity B of the bar 14 to theatmosphere after the extrusion process is over. The shape of the partbeing extruded in periodically checked by applying a template 21 (FIG.3) which may be either flat or three-dimensional. When positioning thetemplate 2] on the part, the former rests on the clamping means 12.

To manufacture convexo-concave pieces such as cylindrical half-rings ordiaphragms, they employ a hydraulic extruder wherein on top of thebillet 4 there is mounted a vessel 22 (FIG. 5) communicating with apressurized liquid supply (not shown), with a plurality of auxiliaryvessels 23 being mounted along a guide member fixed in the head of thevessel 22 with one end thereof. The edges of the auxiliary vessels 23are pressed against the billet 4 in the interspaces between the edges ofthe auxiliary vessels 3 disposed therebeneath, so that between thebillet 4 and each pair of adjacent vessels 23 airtight cavities C areformed. Each of the cavities C is hydraulically connected to apressurized liquid supply (not shown). Just as with the auxiliaryvessels 3, the areas of the inner and outer surfaces of the auxiliaryvessels 23 are determined by the difference in the loads they experiencefrom the pressure of the liquid in the cavities C adjoining each vessel23 on both sides. And the pressure inside the vessel 23 is somewhatlower than that outside it, thereby ensuring that the joints between theedges of the vessels 23 with the seals 5 and the billet 4 remainairtight throughout the extrusion process. The vessels 23 are disposedin the vessel 22 so as to reciprocate freely along the guide memberinstalled in the head thereof.

A hollow bar 24 identical with the one used for the vessels 3 isemployed as the guide member. Over the bar 24 having a cavity D thereare fitted springs 25 constraining the vessels 23 to stay apart one fromanother and pressing them to the billet 4. There is a stop 26 with a setscrew (not shown) fitted on the upper end (as shown in the drawing) ofthe bar 24, i.e., beyond the vessel 22, which stop 26 serves to set theauxiliary vessels 23 in position for the start of operation.

As the cavities C are filled with the liquid, the air escapes therefromthrough a connecting pipe 27 and float valves 28.

Each float valve 28 is installed at a portion of a conduit 29 which runsparallel to the guide bar 14. The other portion of each conduit 29 isdisposed in the respective cavity C between the vessels 23 and thebillet 4 and terminates in the upper portion (as shown in the drawing)of the cavity C. At the point where one portion of the conduit 29adjoins the other the conduit 29 is fastened to the edge of therespective auxiliary vessel 23.

Besides, the float valves 28 are used as pointers indicating thedisplacements of the auxiliary vessels 23 in the process of part shapingso as to monitor the part shape by the magnitude of such displacements.

At the points where the conduits 29 pass through the walls of theauxiliary vessels 23 there are airtight inlets 30 fitted into the walls.

In an alternative embodiment of the invention, each of the auxiliaryvessels 3 or 23 is provided with a bushing 31 (FIG. 6) disposed adjacentthe head of the vessel and fitted over the guide member of the vessel,viz. the hollow bar 14.

The bushing 31 carries a spring 16 which keeps the auxiliary vessels 3or 23 apart one from another. The bushings 31 of adjacent auxiliaryvessels 3 or 23 and adapted to telescopically fit one inside another soas to be able to move relative to one another in the process of partshaping. This kind of coupling of the auxiliary vessels 3 or 23 with thebar 114 is used in those cases when the pressure of the liquid in eachsuccessive cavity A or C formed with the peripheral portion of thebillet 4 steadily rises, with the result that the area differential ofthe projections of the outer and inner surfaces of each of the auxiliaryvessels 3 or 23, at a constant thickness of the vessel walls, will bedetermined by the wall thickness of the bushing 31. By varying the wallthickness of the bushing 31 it is possible to meet the abovementionedcondition as to the ratio of the liquid pressure values on the insideand outside of the auxiliary vessels 3 or 23.

The proposed hydrualic extruder operates in the following manner.

In the initial position before the start of operation, the reducingvalves 8 are adjusted to a pressure valve roughly equal to a third ofthe service pressure required deforming the billet 4. The bar 14 (FIG.3) is driven by the rod 18 of the hydraulic cylinder 17 to the extremelower position where it constrains the auxiliary vessels 3 kept apart bythe springs 16 in a position wherein the edges thereof are level with orsomewhat lower than the edge of the vessel 1. Then the billet 4 ispositioned on the edges of the vessel 1 without pressing the formerthereto, following which liquid is supplied into each cavity A throughthe reducing valves 8 and into the cavity B of the bar 14 through theT-valve 19 until all the cavities A have been filled. The clamping means12 is mounted on the billet 4 and fixed on the vessel 1. Then thepressure in the hydraulic cylinder 1 is reduced to the atmospheric levelin order to unlock the bar 14 and enable the bar flange 20 and thevessels 3 to be forced by the springs 16 upward until the seal 5 on theflange 20 and the edges of the vessels 3 come into close contact withthe billet 4, dividing same into a plurality of zones. After that theliquid from the pressurized supply 6 is supplied successively .nto eachof the cavities A, the pressure value value being regulated by thereducing valves 8. The pressure in each cavity A depends on the shape ofthe part being extruded, on the mechanical properties of the billetmaterial, its thickness and the radius of curvature of the part in eachzone; this pressure value is determined by computation. As the pressurein the cavities A varies the billet 4 is being shaped into the requiredpart, the evolving shape periodically checked by applying the template21.

As the liquid is simultaneously supplied under different pressures todifferent zones of the billet 4, the thickness of the billet is changeduniformly in the process of deformation. As a result, the part producedhas a wall thickness within reasonable limits of accuracy. To preventloss of stability of that zone of the billet 4 which adjoins theclamping means 12 as the part is being extruded, this zone is deformedat a pressure somewhat higher than that required for its deformation.The central zones of the billet 4 experience a pressure not exceedingthe deformation pressure.

Upon completion of the hydraulic extrusion process, the reducing valves8 are closed and the valves of the conduits 7 are opened, causing partof the liquid to flow out of all cavities A and out of the cavity B backto the supply source 6, so that the pressure in all these cavities dropsto the atmospheric level.

Then the T-valve 19 is set in a position wherein the cavity B isconnected to the atmosphere, and the bar 14 is moved by the rod 18 ofthe hydraulic cylinder 17 downward to its initial position, causing theseals on the edges of the vessels 3 to be detached from the part, andthe liquid from the cavities'A and B flows by gravity back to the source6. Then the clamping means 12 is removed and the finished part is takenoff the vessel 1 of the extruder.

The mean wall thickness error of the parts manufactured by the proposedtechnique was shown by tests to stay within 5 per cent, whereas similarparts manufactured out of the same material by the prior art method onthe prior device have a wall thickness error as high as 10 per cent.These data were obtained in the manufacture of a vessel bottom ofdiameter 205 and height The device in accordance with the inventioncomprised two cavities; liquid at a pressure of 12 atm. was suppliedinto the central cavity and at a pressure of atm. into the other one.The material of the billet was an aluminum alloy,

The hydraulic extruder of FIG. 5 is employed to manufactureconvexo-concave parts; its principle of operation is as follows.

The guide bar 14 is driven by the rod of the hydraulic cylinder 17 toits extreme lower position, while the bar 24 is moved to its extremeupper position and fixed therein with the help of the stop 26. In thisposition, the auxiliary vessels 3 are arranged below the joint line ofthe vessels 1 and 22, while the auxiliary vessels 23 are arranged abovethat line. Then, the vessel 22 together with the auxiliary vessels 23and the bar 24 is removed from the vessel 1, whereupon liquid issupplied into the cavities A and B until the vessel 1 has been filled.After that the billet 4 is positioned on the vessel 1, the vessel 22with the auxiliary vessels 23 is placed on the billet 4 and fastened tothe vessel 1 by bolts (not shown), en-

suring that the edge of the billet 4 is pressed to the vessels l and 22with a required force. Then, with the help of the hydraulic cylinder 17and its rod 18, the bar 14 is drived upward until the flange 20 has comeinto contact with the billet 4, thereby releasing the springs 16 so thatthe vessels 3 move upward until their edges come into contact with thebillet 4 by way of the sealings 5 of the vessel edges. Then the stop 26is unlocked so that the springs 25 force the bar 24 and the auxiliaryvessels 23 into contact with the billet 4.

The cavity D of the bar 24 and the cavities C are filled with liquiduntil the air has completely escaped through the connecting pipe 27 andthe conduits 29 with the valves 28, whereupon the valves 28 are closed.

After that the liquid again starts to be supplied into the cavities A,B, C and D at a pressure roughly equal to a third of the deformationpressure of the billet 4 in order to seal off the cavities A, B, -C andD. This completed, the pressure in each of the cavities is graduallyraised to a predetennined value and the billet 4 is deformed.

In the process of deformation of the billet 4, the conduits 29 with thevalues 28 rigidly coupled with the edges of the auxiliary vessels 23 aredisplaced therewith, so that the displacements of certain points of thebillet 4 in the process of extrusion can be measured, affording apossibility of monitoring the evolving shape of the part. In order toimprove the quality of shape control, the auxiliary vessels 3, too, havesimilar displacement pointers.

With the edges of the auxiliary vessels 23 disposed in the interspacesbetween the edges of the vessels 3, the shape control quality rises;furthermore, such an arrangement, whereby the billet is divided into aplurality of zones experiencing different pressures, broadens the scopeof the proposed extruder. By the right choice of the pressures exertedon the different zones of the billet 4, convexo-concave parts ofintricate shapes may be manufactured.

Since each of the zones of the billet 4 is relatively small in size, therisk of loss of stability of the billet 4, particularly near the pointwhere the billet 4 is squeezed between the vessels 1 and 22, is all butnonexistent.

Besides, with the liquid on both sides of the billet 4 exerting pressurethereupon, the material of the billet 4 is subjected to compressivestresses, which is another factor preventing the loss of stability ofthe billet 4 and permitting the depth of extrusion to be increased.

Upon completion of the shaping process, the pressure of the liquid inthe cavities A, B, C and D is brought down to the atmospheric level.Then the bar 14 is driven downward to ensure communication of thecavities A one with another and with the cavity B of the bar- 14,whereas the bar 24 is driven upward to ensure communication of thecavities C one with another and with the cavity D of the bar 24. Theconnecting pipe 27 is opened, venting the cavities C to the atmosphere.This causes part of the liquid to flow back to the supply source throughthe conduits l0 and 7. The remaining liquid is pumped out of thecavities C through the cavity D of the bar 24, simultaneously openingthe T-valve 19, and venting the cavity B of the bar 14 to theatmosphere. This wll cause the air to force the liquid out of thecavities A and B through the conduits 7 and 10 back to the supplysource.

Finally, the vessels 1 and 22 are separated and the finished part isremoved.

Just as in the case described hereinabove, should the billet 4 besmaller in size than the cross-section of the vessels 1 and 22, then useis made of plates 13 disposed on both sides of the billet 4. The plates13 are clamped together with the billet 4 between the vessels 1 and 22,and pressurized liquid is supplied into the cavities A and C spanned bythe plates 13, so that the pressure of the liquid clamps the plates 13to the billet 4, thereby providing for the displacement of the edge ofthe billet 4 as it is being deformed without loss of stability.

What we claim is:

l. A device for hydraulically extruding a part out of a sheet metalworkpiece comprising, a vessel on which said workpiece is mounted; apressurized liquid supply communicating with said vessel; clamping meansfor fastening said workpiece onto said vessel about the peripherythereof; a guide member installed with one end thereof in the head ofsaid vessel; a plurality of auxiliary vessels sequentially mounted onsaid guide member so to reciprocate freely therealong and adapted to fitone into another; said auxiliary vessels having edges pressed againstsaid workpiece to define between same and said adjacent vesselshermetically sealed cavities; said cavities being defined by saidauxiliary vessels and said workpiece, each said cavity beinghydraulically connected to said pressurized liquid supply, the areas ofthe outer and inner surfaces of each one of said auxiliary vessels beingdetermined by the difference in loads exerted thereupon by the pressureof the liquid in said cavities adjoining said vessel on both sides, sothat the load inside said vessel is substantially smaller than thatoutside said vessel.

2. A device as of claim 1, wherein a vessel communicating with apressurized liquid supply is mounted on said workpiece; a guide membercarrying a plurality of sequentially arranged auxiliary vessels able toreciprocate freely along said guide member and adapted to fit one intoanother, said guide member being installed in the head of said vesselwith one end thereof, the edges of said auxiliary vessels being pressedagainst said workpiece in .the interspaces between the edges of theauxiliary vessels disposed beneath said workpiece, so that betweenadjacent vessels and said workpiece there are defined hermeticallysealed cavities, each of which is hydraulically connected to thepressurized liquid supply, the areas of the outer and inner surfaces ofeach of the auxiliary vessels being determined by the difference in theloads exerted thereupon by the pressure of the liquid in the cavitiesadjoining the vessel on both sides so that the load inside the vessel issubstantially smaller than that outside that vessel.

3. A device as of claim 1, wherein said guide member is a hollow barcoupled with the movable member of a hydraulic cylinder, said hollow barcarrying springs sequentially fitted thereover, said springsconstraining the auxiliary vessels to stay at a certain distance onefrom another and pressing the auxiliary vessels against said workpieceprior to the start of operation.

4. A device as of claim 2, wherein said guide member is a hollow barcoupled with the movable member of a hydraulic cylinder, said hollow barcarrying springs sequentially fitted thereover, said springsconstraining the auxiliary vessels to stay at a certain distance onefrom another and pressing the auxiliary vessels against said workpieceprior to the start of operation.

5. A device as of claim 1, including a plate fastened to the billet andto the vessel by clamping means between the vessel and the saidworkpiece, said plate having a hole defined therein to fit the contourof said workpiece in plan and spanning a plurality of the cavities toexclude same from taking part in the shaping process.

6. A device as of claim 2, including at least one plate fastened to thebillet and to the vessel by clamping means between the vessel and thesaid workpiece and having therein a hole conforming in shape to thecontour of said workpiece in plan.

7. A device as of claim 2, wherein each of the auxiliary vesselsdisposed above said workpiece houses a conduit rigidly coupled therewithto vent air out of said vessel as same is being filled with liquid, saidconduit with an outlet near the edge of the vessel having a portionextending beyond the confines of the device, the latter portion of theconduit being parallel to the guide member and comprising a valve, saidvalve being also means of visual control over the displacements of thevessel as said workpiece is being deformed.

8. A device as of claim 3, wherein each of the auxiliary vessels has abushing adjoining the head thereof and fitted over said guide bar, saidbushing carrying a spring separating one auxiliary vessel from another,the bushings of adjacent auxiliary vessels being adapted totelescopically fit one into another.

1. A device for hydraulically extruding a part out of a sheet metalworkpiece comprising, a vessel on which said workpiece is mounted; apressurized liquid supply communicating with said vessel; clamping meansfor fastening said workpiece onto said vessel about the peripherythereof; a guide member installed with one end thereof in the head ofsaid vessel; a plurality of auxiliary vessels sequentially mounted onsaid guide member so as to reciprocate freely therealong and adapted tofit one into another; said auxiliary vessels having edges pressedagainst said workpiece to define between same and said adjacent vesselshermetically sealed cavities; said cavities being defined by saidauxiliary vessels and said workpiece, each said cavity beinghydraulically connected to said pressurized liquid supply, the areas ofthe outer and inner surfaces of each one of said auxiliary vessels beingdetermined by the difference in loads exerted thereupon by the pressureof the liquid in said cavities adjoining said vessel on both sides, sothat the load inside said vessel is substantially smaller than thatoutside said vessel.
 2. A device as of claim 1, wherein a vesselcommunicating with a pressurized liquid supply is mounted on saidworkpiece; a guide member carrying a plurality of sequentially arrangedauxiliary vessels able to reciprocate freely along said guide member andadapted to fit one into another, said guide member being installed inthe head of said vessel with one end thereof, the edges of saidauxiliary vessels being pressed against said workpiece in theinterspaces between the edges of the auxiliary vessels disposed beneathsaid workpiece, so that between adjacent vessels and said workpiecethere are defined hermetically sealed cavities, each of which ishydraulically connected to the pressurized liquid supply, the areas ofthe outer and inner surfaces of each of the auxiliary vessels beingdetermined by the difference in the loads exerted thereupon by thepressure of the liquid in the cavities adjoining the vessel on bothsides so that the load inside the vessel is substantially smaller thanthat outsidE that vessel.
 3. A device as of claim 1, wherein said guidemember is a hollow bar coupled with the movable member of a hydrauliccylinder, said hollow bar carrying springs sequentially fittedthereover, said springs constraining the auxiliary vessels to stay at acertain distance one from another and pressing the auxiliary vesselsagainst said workpiece prior to the start of operation.
 4. A device asof claim 2, wherein said guide member is a hollow bar coupled with themovable member of a hydraulic cylinder, said hollow bar carrying springssequentially fitted thereover, said springs constraining the auxiliaryvessels to stay at a certain distance one from another and pressing theauxiliary vessels against said workpiece prior to the start ofoperation.
 5. A device as of claim 1, including a plate fastened to thebillet and to the vessel by clamping means between the vessel and thesaid workpiece, said plate having a hole defined therein to fit thecontour of said workpiece in plan and spanning a plurality of thecavities to exclude same from taking part in the shaping process.
 6. Adevice as of claim 2, including at least one plate fastened to thebillet and to the vessel by clamping means between the vessel and thesaid workpiece and having therein a hole conforming in shape to thecontour of said workpiece in plan.
 7. A device as of claim 2, whereineach of the auxiliary vessels disposed above said workpiece houses aconduit rigidly coupled therewith to vent air out of said vessel as sameis being filled with liquid, said conduit with an outlet near the edgeof the vessel having a portion extending beyond the confines of thedevice, the latter portion of the conduit being parallel to the guidemember and comprising a valve, said valve being also means of visualcontrol over the displacements of the vessel as said workpiece is beingdeformed.
 8. A device as of claim 3, wherein each of the auxiliaryvessels has a bushing adjoining the head thereof and fitted over saidguide bar, said bushing carrying a spring separating one auxiliaryvessel from another, the bushings of adjacent auxiliary vessels beingadapted to telescopically fit one into another.